When user tries to replace the user-defined control TLV, the kernel
checks the change of its content via memcmp(). The problem is that
the kernel passes the return value from memcmp() as is. memcmp()
gives a non-zero negative value depending on the comparison result,
and this shall be recognized as an error code.
The patch covers that corner-case, return 1 properly for the changed
TLV.
Fixes: 8aa9b586e420 ("[ALSA] Control API - more robust TLV implementation")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
sound/core/control.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sound/core/control.c b/sound/core/control.c
index 3c6be1452e35..4525e127afd9 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -1137,7 +1137,7 @@ static int snd_ctl_elem_user_tlv(struct snd_kcontrol *kcontrol,
mutex_lock(&ue->card->user_ctl_lock);
change = ue->tlv_data_size != size;
if (!change)
- change = memcmp(ue->tlv_data, new_data, size);
+ change = memcmp(ue->tlv_data, new_data, size) != 0;
kfree(ue->tlv_data);
ue->tlv_data = new_data;
ue->tlv_data_size = size;
--
2.14.0
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